1. Field of the Invention
The present invention relates to a laminated heat exchanger for use in refrigerators or the like.
2. Prior art
Known laminated heat exchangers generally include a plurality of alternate layers of tube elements and fins laminated with one another. A typical example of such known laminated heat exchangers is disclosed in Japanese Patent Laid-open Publication No. 61-211694.
The disclosed heat exchanger, as reillustrated here in FIGS. 9 and 10 of the accompanying drawings, includes a plurality of tube elements 1 each of which is composed of a pair of stamped plates each having at its one end a pair of juxtaposed bowl-shaped tank-forming recessed portions 12, and an elongate channel-forming recessed portion 5 exteding from the tank-forming recessed portions 12. The two stamped plates are joined together in such a manner that the respective tank-forming recessed portions 12, 12 jointly form a pair of tanks 14, and the respective channel-forming recessed portions 5, 5 jointly form a channel 6 for the passage therethrough of a heat transferring medium. The adjacent tube elements 1, 1 are joined together with their tank-forming recessed portions 12 held in abutment with each other. The tank-forming recessed portions 12 have connecting holes 24 through which the tanks 14 of the adjacent tube elements 1 communicate with each other.
The heat tansferring medium supplied into the heat exchanger flows through the connecting holes 24 into the tanks 14 then is guided along the channels 6 in the respective tube elements 1.
The two tanks 14 are provided for each of the tube elements land hence the abutting tank-forming recessed portions 12 must have overlapping areas for joining the tanks of the adjacent tube elements 1. Since such overlapping areas extend around the connecting holes 26, they per se form blocking walls or barriers 25 which will increase the flow resistance between the tanks 14 of the adjacent tube elements 1. Particularly where the heat exchanger is used as an evaporator in a refrigerating cycle, there is a difficulty that a lubricating oil contained in a refrigerant is prevented by the barriers 25 from retruning to a compressor.